linux/arch/arm64/mm/pgd.c
Will Deacon 39b5be9b42 arm64: mm: move pgd_cache initialisation to pgtable_cache_init
Initialising the suppport for EFI runtime services requires us to
allocate a pgd off the back of an early_initcall. On systems where the
PGD_SIZE is smaller than PAGE_SIZE (e.g. 64k pages and 48-bit VA), the
pgd_cache isn't initialised at this stage, and we panic with a NULL
dereference during boot:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000

  __create_mapping.isra.5+0x84/0x350
  create_pgd_mapping+0x20/0x28
  efi_create_mapping+0x5c/0x6c
  arm_enable_runtime_services+0x154/0x1e4
  do_one_initcall+0x8c/0x190
  kernel_init_freeable+0x84/0x1ec
  kernel_init+0x10/0xe0
  ret_from_fork+0x10/0x50

This patch fixes the problem by initialising the pgd_cache earlier, in
the pgtable_cache_init callback, which sounds suspiciously like what it
was intended for.

Reported-by: Dennis Chen <dennis.chen@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-05 15:43:10 +00:00

60 lines
1.5 KiB
C

/*
* PGD allocation/freeing
*
* Copyright (C) 2012 ARM Ltd.
* Author: Catalin Marinas <catalin.marinas@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/tlbflush.h>
#include "mm.h"
static struct kmem_cache *pgd_cache;
pgd_t *pgd_alloc(struct mm_struct *mm)
{
if (PGD_SIZE == PAGE_SIZE)
return (pgd_t *)__get_free_page(PGALLOC_GFP);
else
return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
if (PGD_SIZE == PAGE_SIZE)
free_page((unsigned long)pgd);
else
kmem_cache_free(pgd_cache, pgd);
}
void __init pgd_cache_init(void)
{
if (PGD_SIZE == PAGE_SIZE)
return;
/*
* Naturally aligned pgds required by the architecture.
*/
pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
SLAB_PANIC, NULL);
}